UPDATE: Tropical Storm Dorian forms; season heats up

Hurricane season gets off to a faster-than-normal start, with four named storms.

BY ZAC ANDERSON

The forces that transform African storms into tropical cyclones spinning toward Florida are aligning earlier than usual, bringing the possibility of a more active hurricane season this year.

The peak of the hurricane season is still a month away but already four named storms have formed, including two that spun off the coast of Africa in the "deep tropics" region that tends to produce the most dangerous Atlantic systems.

The latest, Tropical Storm Dorian, had sustained winds of just over 50 mph, with higher gusts Wednesday. Forecasters are not predicting much strengthening as Dorian heads west on a trajectory that could bring the system near Florida next week.

Since 1950, there have only been five other hurricane seasons when two storms formed in the deep tropics before Aug. 1. All but one of those years produced an above average number of hurricanes, according to an analysis by Phil Klotzbach, a research scientist with Colorado State University's Tropical Meteorology Project.

Klotzbach said conditions for storm development are "relatively favorable, at least more favorable than normal."

On average, it takes until Aug. 20 for four tropical cyclones to form in the Atlantic, said Accuweather meteorologist Andy Mussoline.

"No doubt there's been a fairly fast pace to the season so far," Mussoline said.

But not all signs point to a hectic hurricane season.

Water temperatures are only slightly above normal, nothing like the warm waters that spawned such devastation in 2005 when four storms hit Florida. And air in the eastern Atlantic is still very dry. Hurricanes feed off of moist air.

That tropical systems are forming so early given those conditions "is a bit surprising," Klotzbach said.

Dorian has been helped by low wind shear in the upper atmosphere. Strong upper winds tend to inhibit cyclone formation.

"We have a lot lower shear than normal," Klotzbach said.

That's a bad sign.

"This year I don't think shear is going to be the thing that kills the storms," he said.

At the start of the season Klotzbach and his colleagues predicted 18 named storms in 2013, well above the 12 that occur on average. That forecast will be revised next week, and Klotzbach said he's anguishing over the data.

"There are a lot of mixed signals," he said.

August, September and October are the most active months for hurricanes, with Aug. 20 through Sept. 30 as the peak period.

Meanwhile, meteorologists are keeping an eye on Dorian.

Accuweather expects the system to remain relatively weak, but some strengthening is possible as it approaches the island nations south of Florida. A generally western path is forecast, but there is a possibility the storm could veer north into the open water of the Atlantic, Mussoline said.

"We'll have to certainly keep on eye on it for the Florida peninsula," he said.

EARLIER: The fourth named storm of the 2013 hurricane season formed off the coast of Africa Wednesday and is expected to be near Puerto Rico by Monday.

Tropical Storm Dorian has maximum sustained winds of 50 mph according to the National Hurricane Center.

The system is expected to strengthen in the short term but the long term forecast is less favorable.

Forecasters predict a slight weakening of the system as it passes over cooler waters. Stronger wind shear later in the weak could also prevent the storm from gaining strength.

The tropical cyclone could approach Florida next week if it stays on a western trajectory and maintains strength.

Check back at HeraldTribune.com for more on this developing story.

EARLIER...A new tropical depression has formed in the eastern Atlantic and is expected to soon become a tropical storm.

The depression is centered about 310 miles (500 kilometers) west-southwest of the Cape Verde Islands -- off the western coast of Africa -- moving west-northwest near 20 mph (32 kph). The system's maximum sustained winds early Wednesday were near 35 mph (55 kph), according to the National Hurricane Center, with forecasts calling for the system to reach tropical storm status later today or tonight.

NHC advisors note the system has low-level circulation but currently lacks shower and thunderstorm activity near the center. Additionally, a number of environmental factors stand in the path of the depression gaining strength, including dry, dusty air from the Saharan Desert, cooler water temperatures and some strong winds in the upper parts of the atmosphere.

Because of these obstacles, the system is expected to remain weak through this weekend, likely reaching Puerto Rico on Sunday.SNN meteorologist Cassie Nall contributed to this report.

EARLIER...By Zac Anderson, H-T staff writerA low pressure system off the coast of Africa now has a 60 percent chance of becoming the fourth named storm of the 2013 hurricane season, experts say.

The National Hurricane Center reported Monday morning that the system is expected to strengthen throughout the day, but weather conditions will quickly become less favorable to storm development.

By Wednesday "environmental conditions become less conducive" for the system to gain strength, according to the Hurricane Center.

The system is currently a few hundred miles south, southeast of the Cape Verde Islands. It is moving at 15 to 20 mph. If a tropical cyclone develops it could be near Puerto Rico by the end of the week.

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